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Publication numberUS4918317 A
Publication typeGrant
Application numberUS 07/285,335
Publication dateApr 17, 1990
Filing dateDec 14, 1988
Priority dateJul 2, 1987
Fee statusLapsed
Publication number07285335, 285335, US 4918317 A, US 4918317A, US-A-4918317, US4918317 A, US4918317A
InventorsTodd M. Hess, Peter Gottschalk
Original AssigneeThe Mead Corporation
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Radiation dosimeter
US 4918317 A
Abstract
The present invention provides a radiation dosimeter comprising a support having a layer of microcapsules on the surface thereof. The microcapsules comprise a wall and an internal phase of a solution of a radiochromic dye. Upon exposure to radiation, the radiochromic dye changes color or shade plus density. The radiation dosimeter can be supplied in large as well as small formats.
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Claims(15)
What is claimed is:
1. A radiation dosimeter comprising a support having a layer of microcapsules on the surface thereof, said microcapsules comprising a wall and an internal phase, said internal phase comprisinq a solution of a radiochromic dye, said radiochromic dye solution being capable of changing color or shade plus density upon exposure to gamma, ultraviolet or electron beam radiation.
2. The dosimeter of claim 1 wherein said dosimeter indicates that a threshold level of radiation has been exceeded.
3. The dosimeter of claim 1 wherein said dosimeter provides a quantitative indication of the amount of radiation to which said dosimeter is exposed.
4. The dosimeter of claim 1 wherein said radiochromic dye is dye cyanide.
5. The dosimeter of claim 1 wherein said wall is formed from melamine-formaldehyde or urea-formaldehyde resin.
6. The dosimeter of claim 1 wherein said internal phase includes an ultraviolet absorbing solvent or an ultraviolet absorber.
7. A process for detecting and/or measuring gamma, ultraviolet or electron beam radiation comprising the steps of:
exposing a dosimeter to radiation, said dosimeter comprising a support having a layer of microcapsules on the surface thereof, said microcapsules comprising a wall and an internal phase, said internal phase comprising a solution of a radiochromic dye, said radiochromic dye solution being capable of changing color or shade plus density upon exposure to gamma, ultraviolet or electron beam radiation; and
comparing the color, shade, or density of said radiochromic dyes with a standard to determine the amount of gamma, ultraviolet or electron beam radiation received.
8. The process of claim 7 wherein said dosimeter indicates that a threshold level of radiation has been exceeded.
9. The process of claim 7 wherein said dosimeter provides a quantitative indication of the amount of radiation to which said dosimeter is exposed.
10. The process of claim 7 wherein said radiochromic dye is dye cyanide.
11. The process of claim 7 wherein said wall is formed from melamine-formaldelhyde of urea-formaldehyde resin.
12. The process of claim 7 wherein said internal phase includes an ultraviolet absorbing solvent or an ultraviolet absorber.
13. A process for detecting and/or measuring radiation comprising the steps of:
exposing a radiation dosimeter to radiation, said dosimeter commprising a transparent support having a layer of microcapsules on the surface thereof, said microcapsules comprising a wall and an internal phase, said internal phase comprising a solution of radiochromic dye, said radiochromic dye solution baing capable of changing color or shade plus density upon exposure to gamma, ultraviolet or electron beam radiation; and
determining the amount of gamma, ultraviolet or electron beam radiation received by a spectrophotometer or a densitometer.
14. The process of claim 13 wherein said radiochromic dye is dye cyanide.
15. The process of claim 13 wherein said wall is formed from melamine-formaldehyde or urea-formaldehyde resin.
Description

This is a continuation Application of co-pending application Ser. No. 069,357, filed July 2, 1987.

BACKGROUND OF THE INVENTION

The present invention relates to radiation dosimeters, and more particularly, to radiation dosimeters comprising microencapsulated radiochromic dyes.

Radiation, especially gamma and electron beam, is now widely used in industry. For example, gamma radiation is used in the food industry as a means for killing bacteria and preserving food. It is used in the pharmaceutical industry as a means for sterilizing pharmaceuticals and in the hospital supply industry as a means for sterilizing surgical gloves, surgical drapes, and the like.

Because radiochromic dyes change color or shade plus density upon exposure to radiation, they have been used in radiation dosimeters to determine the amount of radiation which has been received in a given environment. These dyes are gelatinous in nature and they are typically containerized within plastic tubing as disclosed in U.S. Pat. Nos. 4,377,751; 4,489,240; 4,507,226; and 4,602,425; within plastic blocks as disclosed in U.S. Pat. No. 4,631,414; or within glass ampoules as disclosed in U.S. Pat. Nos. 3,710,109 and 4,507,226. U.S. Pat. No. 4,006,023 teaches a dosimeter comprising a vinyl or acrylic polymer having a dye cyanide dispersed therein.

With the increased industrial use of radiation, a need has arisen for a radiation dosimeter which is less expensive and more convenient to use. Also, because currently available radiation dosimeters measure radiation over a small area, a need exists for a radiation dosimeter which can be used in large as well as small formats.

SUMMARY OF THE INVENTION

The present invention provides a radiation dosimeter comprising a support having a layer of microcapsules on the surface thereof. The microcapsules comprise a wall and an internal phase of a solution of a radiochromic dye. As those skilled in the art know, radiochromic dyes change color or shade plus density upon exposure to radiation such as alpha, beta, and gamma radiation; electron beam radiation; x-ray; and ultraviolet radiation.

The present invention includes both digital-type dosimeters in which radiation above a certain threshold amount causes a color or density change and analog-type dosimeters from which the amount of radiation can be determined quantitatively.

In contrast to current dosimeters, the radiation dosimeter of the present invention can be supplied in large as well as small formats. Prior to the present invention, numerous ampoule-type or plastic tubing-type dosimeters had to be placed over a given area in order to properly measure the amount of radiation received by the given area. The radiation dosimeter of the present invention is useful because it can be supplied in the form of single sheets or rolls. Further, the single sheets can be cut to the size required. Depending upon the application, a single sheet can be placed over a given area or a web can be rolled over an area where the radiation received is to be measured. As such, the radiation dosimeter of the present invention is more convenient to use than current dosimeters employing radiochromic dyes while maintaining the accuracy and reliability of current dosimeters in making radiation dose determinations. Further, microencapsulation of radiochromic dyes to produce a radiation dosimeter is less expensive than ampoule or plastic tubing encapsulation of radiochromic dyes.

The present invention also provides a process for detecting and/or measuring radiation. The foregoing radiation dosimeter which comprises a support having a layer of microcapsules on the surface thereof wherein the microcapsules comprise a wall and an internal phase of a solution of radiochromic dyes is exposed to radiation. The radiochromic dyes change color or shade plus density upon exposure to radiation. The color, shade, or density, as viewed through the microcapsule side of the dosimeter or through the support side of the dosimeter if the support is transparent, is then compared with a standard, reference, or comparison scale which is supplied with the dosimeter to determine the amount of radiation received. The amount of radiation received can also be determined by a spectrophotometer or a densitometer. In this regard, it is noted that reference to determining the amount of exposure is intended to encompass both digital dosimeters inwhich the determination is simply that a threshold has been exceeded as well as analog dosimeters in which the determination yields the quantity of radiation.

Thus, an object of the present invention is to provide a radiation dosimeter which is available in large as well as small formats, which is inexpensive, and which is convenient to use.

An additional object of the present invention is to provide digital-type and analog-type dosimeters.

A further object of the present invention is to provide a radiation dosimeter which is exposed to radiation and the amount of radiation received is determined by a spectrophotometer or a densitometer.

A more particular object of the present invention is to provide a radiation dosimeter which provides an accurate and reliable means of making radiation dose determinations.

Other objects and advantages of the present invention will become apparent from the following description and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Any radiochromic dye can be used in the radiation dosimeter of the present invention. Examples of useful radiochromic dyes include dye cyanides such as

4,4',4"-triamino-triphenylacetonitrile;

4,4',4"-triamino-3,3'3"-trimethyl-triphenylacetonitrile;

4,4'-bis-dimethylamino-triphenylacetonitrile;

4,4'-bis-diethylamino-triphenylacetonitrile;

4,4',4"-tris-dimethylamino-triphenylacetonitrile;

4,4',4"-trihydroxytriphenylacetonitrile; and

4,4'-bis-dimethylaminotriphenylacetonitrile-4"-sulfonic acid.

Other examples of useful dye cyanides are pararosaniline cyanide; hexa(hydroxyethyl) pararosaniline cyanide; new fuchsin cyanide; crystal violet cyanide; malachite green cyanide; brilliant blue cyanide; methyl green cyanide; helvetia green cyanide; and seto-glaucine cyanide. Most of the foregoing dye cyanides are available from Far West Technologies.

To form the internal phase of the microcapsules, solutions of the radiochromic dyes in a photo-activating solvent are prepared. The solvent should be colorless so that the amount of radiation received can be determined either visually or instrumentally based on the color change in the radiochromic dye.

Preferably, a polar solvent is used. High polarity solvents facilitate dissolving greater amounts of dye therein. Also, high polarity solvents seem to enhance the sensitivity of the dye in the color change reaction.

The solvents should remain liquid down to at least about 20° C. and should not boil or vaporize at temperatures below about 80° C. The solvents should be composed of light elements such as carbon, hydrogen, and oxygen and should be relatively free of elements having atomic numbers greater than 17 which might impair sensitivity.

Examples of useful solvents are water; ethyl alcohol; methyl alcohol; i-propyl alcohol; formamide; dimethyl formamide; diethyl formamide; dimethyl acetamide; N,N-dimethyl formamide; N,N-diethyl formamide; N,N-dimethylacetamides; 2-methoxy ethanol; 2-ethoxy ethanol; triethyl phosphate; tributyl phosphate; trioctyl phosphate; trichloroethyl phospaate; dimethyl sulfoxide; ethylene glycol; propylene glycol; acetic acid; 2-chloro ethanol; and vinyl pyrollidone. Preferably, because of current microencapsulation methodology, the solvent should be water insoluble.

Other examples of useful solvents are polyoxy compounds containing at least one ether group such as ethylene glycol monomethyl ether; ethylene glycol monoethyl ether; ethylene glycol diethyl ether; and tetraethylene glycol dimethyl ether.

The concentration of the dye in the solvent should be from about 3 to 20 percent by weight, and preferably, about 10 to 15 percent by weight, which in most instances is approaching or about the saturation concentration of the dye. Preferably, relatively high concentrations of dye are used in the polar solvent.

The dyes are dissolved in the solvent by conventional means. For example, the powdered dye can be poured into a beaker of solvent and the beaker subjected to ultrasonic vibration until all of the dye has dissolved in the solvent.

After the dye has been dissolved in the solvent, small amounts of acid can be added to the solution. The acid proves beneficial in enhancing the color-forming abitlity of the dye and its stability in solution. The acid stabilizes the dye so that it does not revert back to the clear, colorless form. When a solution of radiochromic dyes goes from clear to color upon exposure to radiation, the solution loses some of its acidity. One purpose of the acid addition is to ensure that the solution remains acidic and that some acid groups are available for reaction with the dyes so that the color change is stabilized.

To assure permanency of the color change, about 1% acid is added to the solution to make the solution slightly acidic with a pH of about 5 to 7. Useful acids are acetic acid; arachidic acid; barbituric acid; boric acid; cinnamic acid; citric acid; coumalic acid; cyanoacetic acid; maleic acid; phosphoric acid; phthalic acid; salicylic acid; styrylacetic acid; and tartaric acid. The acids should dissolve in the solvent in which they are employed and should be subsequently free of water.

The internal phase of radiochromic dye in solvent is encapsulated in a conventional manner. Microencapsulation has been accomplished by a wide variety of known techniques including coacervation, interfacial polymerization, polymerization of one or more monomers in an oil, as well as various melting, dispersing, and cooling methods.

Many known wall-forming materials are useful for encapsulation of the internal phase of the present invention. Examples of useful wall-forming materials are gelatin wall-forming materials (see U.S. Pat. Nos. 2,730,456 and 2,800,457 to Green et al.) including gum arabic, polyvinyl alcohol, carboxymethylcellulose; resorcinol-formaldehyde wall formers (see U.S. Pat. No. 3,755,190 to Hart et al.); isocyanate wall-formers (see U.S. Pat. No. 3,914,511 to Vassiliades); isocyanate-polyol wall-formers (see U.S. Pat. No. 3,796,669 to Kiritani et al); urea-formaldehyde wall-formers, and more particularly, urea-resorcinol-formaldehyde (in which oleophilicity is enhanced by the addition of resorcinal) (see U.S. Pat. Nos. 4,001,140; 4,087,376; and 4,089,802 to Foris et al); melamine-formaldehyde resin and hydroxypropyl cellulose (see commonly assigned U.S. Pat. No. 4,025,455 to Shackle). To the extent necessary for complete disclosure of these wall-forming materials, the above mentioned patents are specifically incorporated by reference. Typically the microcapsules range from about 5 to 30 microns in size.

The formed capsule wall must be transmissive to exposure radiation. Preferably, the wall-forming material is melamine-formaldehyde or urea-formaldehyde.

Once the microcapsules are formed, the microcapsules can be combined with a binder. A wide variety of suitable binders exists. Examples of useful binders are gelatin, polyvinyl alcohol, polyacrylamide, and acrylic latices.

The coating composition of microcapsules and binder is applied to a continuous web of paper and dried. Any ordinary coating or printing technique can be used in making the radiation dosimeters in accordance with the present invention including such means as roller or blade coating.

The coating composition is applied to a support such as paper. The paper may be a commercial impact raw stock or a special grade paper such as clay-coated paper. As will be discussed later, a transparent support is used when a spectophotometer is used to determine the amount of radiation received. A useful transparent support is polyethylene terephthalate.

As discussed earlier, the radiation dosimeter can be supplied in roll form when large formats are desired. The radiation dosimeter can also be supplied in roll form with a shorter width by cutting the radiation dosimeter material along its length with a pair of opposed circular knives. Such knives rotate at an angle to one another so as to produce a scissoring action between them which cuts the radiation dosimeter material. The radiation dosimeter can be supplied in still smaller formats by cutting as desired.

Radiochromic solutions prepared in accordance with the present invention respond to alpha, beta, and gamma radiation; electron beam radiation; x-ray; and ultraviolet radiation. However, the radiochromic solutions can be desensitized to ultraviolet radiation as will be discussed later.

As previously indicated, two types of dosimeters may be prepared in accordance with the present invention. One indicates that a threshold radiation level has been exceeded. The other provides a quantitative indication of the amount of radiation. These dosimeters are obtained by controlling the internal phase composition.

After exposing a radiation dosimeter to radiation, the resulting density of the radiochromic dye can be examined, by viewing through the microcapsule side of the dosimeter or through the support side of the dosimeter if the support is transparent, to determine the amount of radiation received.

Those skilled in the art will appreciate that it is also possible to design dosimeters in which the amount of radiation is indicated by the color or shade of the chromophoric structure formed. For example, a dosimeter can be prepared in which the layer of microcapsules includes a mixture of two or more sets of microcapsules containing different radiochromic dyes. If the coating composition includes a uniform mixture of these two types of microcapsules, the color produced will vary in both shade and color as a function of the amount of radiation received.

Shade or color differences can also be achieved by blending mixtures of microcapsules containing different radiochromic dyes and different solvents. If one microcapsule is more sensitive than another, a shade or color difference will result which is dependent on the amount of radiation.

The dosimeters of the present invention are useful in a wide variety of applications; however, two applications, in which they find particular use, are food irradiation mapping and dose mapping in diagnostic applications.

In order to determine the amount of radiation received, the dosimeter will typically be accompanied by a standard, comparison, or reference strip. If the dosimeter is a threshold type unit, this strip may be unnecessary. Radiation exceeding the threshold limit will typically be indicated by disappearance or appearance of a reference color.

In quantitative or analog dosimeters, some form of standard, comparison, or reference will be necessary. This reference may be separate from or integral with the dosimeter. Of course, the reference strip can consist of a pre-printed form displaying the density and/or color shade scale and the corresponding dosage level. Alternatively the reference strip can be formed integral with the dosimeter which can be accomplished by, for example, including markings along one border of the dosimeter indicating quantitative dosage levels and exposing the dosimeter in the border region in amounts corresponding to the markings.

In addition to visually measuring the amount of radiation received by comparing the color or shade formed, the color or shade can also be measured instrumentally by a spectrophotometer. The spectrophotometer can measure, through the transparent support of the dosimeter, the apparent transmission as a function of wavelength of the color or shade formed. Useful spectrophotometers are commercially available.

A densitometer equipped to measure the reflectance of the colored materials can also be used. A densitometer measures the reflectance through the microcapsule side of the dosimeter. As such, when using a densitometer, the support can be opaque or transparent. Useful densitometers are commercially available.

The radiochromic dyes used in the present invention are usually sensitive to ultraviolet radiation. In order to compensate for ambient light handling, a standard is typically run for comparative purposes.

As an alternative to running a standard, the radiation dosimeter can be ultraviolet radiation desensitized. For example, the internal phase of the microcapsules can be modified to include a solvent which is highly absorbing in the narrow ultraviolet range in which the radiochromic dyes are sensitive. In another example, the internal phase of the microcapsules can be modified to include an ultraviolet absorber which is highly absorbing in the narrow ultraviolet range in which the radiochromic dyes are sensitive.

Any solvent which absorbs ultraviolet radiation in the narrow range in which the radiochromic dyes are sensitive, is capable of dissolving adequate amounts of the radiochromic dye, and is non-toxic can be used in the foregoing ultraviolet light desensitization application. If the solvent does not meet all of the preceding criteria, the solvent can be modified to be useful in the foregoing application. For example, if a solvent is not ultraviolet absorbing over the entire range in which the radiochromic dyes are sensitive, appropriate ultraviolet absorbers can be use in conjunction with the solvent in order to provide an ultraviolet light desensitized radiation dosimeter.

An example of an ultraviolet radiation desensitized liquid to be microencapsulated is 57.0 wt % propylene carbonate; 38.0 wt % diethyl phthalate; and 5.0 wt % fuchsin-cyan dye. Although not ultraviolet absorbing, propylene carbonate has a high dissolution affinity for the dye. Fuchsin-cyan dye is sensitive in the 290 to 350 nm wavelength range as well as to nuclear radiation. Diethyl phthalate is ultraviolet absorbing in the 250 to 340 nm wavelength range, and as such, absorbs in all but 10 nm of the ultraviolet range in which the radiochromic dye is sensitive.

In lieu of an ultraviolet absorbing solvent, appropriate ultraviolet absorbers could be included in the solvent of the microcapsule internal phase and/or in the binder if one is used.

The radiation dosimeter of the present invention is also useful as an electron beam imaging material. For example, the dosimeter can be image-wise exposed to radiation to produce an image in the form of a color change in the radiochromic dyes.

The present invention is more fully illustrated by the following non-limiting Example.

EXAMPLE

The microencapsulation procedure was as follows. 353.0 g Distilled Water and 7.0 g Versa TL-500 were stirred for 15 min at 500 rpm. 8.0 g Pectin and 0.16 g NaHCO3 were stirred for 2 hr. at 2000 rpm. The melamine-formaldehyde condensate was prepared as follows. 10.86 g Melamine with 122.22 g water was stirred. 18.03 g 37% Formaldehyde was added. The pH was adjusted to 8.5 with 10% NaOH. The solution was heated to 60° C. After the solution cleared, the solution was heated an additional 40 minutes at 60° C. The solution was cooled to 30° C. which took approximately 30 min. The water phase was pH adjusted to 6.0 with NaOH. The following internal phase was emulsified for 15 min. at 3000 rpm: 38.04 g Diethyl Phthalate; 57.12 g Propylene Carbonate; 5.02 g New Fuchsin-CN; and 6.77 g N-100 (Isocyanate). The internal phase was heated at 60° C. until the dye dissolved. The melamine-formaldehyde condensate was added and cured for 1 hr. at 70° C. and 3000 rpm. 46.2 g of 50% urea solution was added and cured for 1 hr. more at 70° C. and 3000 rpm. The solution was cooled and stirred overnight at 500 rpm.

The microcapsules were prepared as follows. A 50/50 weight water/capsule composition was centrifuged on 1/2 speed at 1000 rmp for 10 minutes. The liquid was decanted. The following coating solution was prepared: 50 wt % centrifuged solids; and 50 wt % Union Carbide's vehicle 443 binder. The coating solution was mixed well for approximately 10 minutes.

A film was prepared as follows. Hand draw downs were prepared with a #40 Meier bar. Specifically, a Kindura FPG 150 (78#) was coated three times (326.4 microns or 12.85 mils coating thickness) with the composition prepared above. The coatings were partially dried by an air gun followed by complete air drying.

Radiation testing occurred as follows.

______________________________________Cobalt Source - Gamma IrradiationDose, Mrad     Color Density______________________________________0              0.111.76           0.152.98           0.22______________________________________

Color densities may be increased or even decreased for these same dose points by varying dye composition, the type of dye used, or the type(s) of solvents(s) used in the internal phase. Dye activators have previously been found to also increase color density. An example is the inclusion of 2-Imidazoline and Citric Acid in 5 wt % or less quantities.

Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2730456 *Jun 30, 1953Jan 10, 1956Ncr CoManifold record material
US2800457 *Jun 30, 1953Jul 23, 1957Ncr CoOil-containing microscopic capsules and method of making them
US2953454 *Apr 23, 1957Sep 20, 1960Ncr CoPhototropic data storage capsules and base coated therewith
US3710109 *May 27, 1970Jan 9, 1973Chalkley LPrecision dosimetry of high energy radiation
US3732119 *Nov 5, 1968May 8, 1973Ncr CoTemperature sensitive visual display device
US3755190 *Nov 9, 1971Aug 28, 1973NcrCapsule manufacture
US3796669 *Apr 28, 1971Mar 12, 1974Fuji Photo Film Co LtdProcess for the production of oily liquid-containing microcapsules and the microcapsules produced thereby
US3914511 *Oct 18, 1973Oct 21, 1975Champion Int CorpSpot printing of color-forming microcapsules and co-reactant therefor
US4001140 *Jul 10, 1974Jan 4, 1977Ncr CorporationCapsule manufacture
US4006023 *Oct 7, 1974Feb 1, 1977The United States Of America As Represented By The Secretary Of The Department Of Health, Education And WelfarePhotographic polymeric composition containing a leuco dye cyanide
US4025455 *Apr 2, 1976May 24, 1977The Mead CorporationCross-linked hydroxypropylcellulose microcapsules and process for making
US4087376 *Dec 30, 1976May 2, 1978Ncr CorporationCapsule manufacture
US4089802 *Dec 30, 1976May 16, 1978Ncr CorporationCapsule manufacture
US4377751 *May 28, 1981Mar 22, 1983The United States Of America As Represented By The Secretary Of The ArmyOptical waveguide dosimeter
US4399209 *Nov 12, 1981Aug 16, 1983The Mead CorporationTransfer imaging system
US4454421 *Sep 18, 1981Jun 12, 1984Japan Atomic Energy Research InstituteApparatus for measuring radiation dose
US4466941 *Feb 11, 1982Aug 21, 1984Evreka, Inc.Photosensitive compositions and products
US4489240 *Nov 15, 1982Dec 18, 1984Stanley KronenbergRadiochromic leuko dye real time dosimeter, one way optical waveguide
US4507226 *Mar 2, 1982Mar 26, 1985Bicron CorporationRadiochromic liquid solution
US4602425 *Sep 26, 1985Jul 29, 1986The United States Of America As Represented By The Secretary Of The ArmyMethod of protecting a radiochromic optical waveguide dosimeter from adverse temperature effects
US4631414 *Sep 20, 1985Dec 23, 1986The United States Of America As Represented By The Secretary Of The ArmyRadiological instrument
US4788126 *May 20, 1987Nov 29, 1988The Mead CorporationRadiation dosimeter and method for measuring radiation dosage
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5411835 *Dec 1, 1993May 2, 1995Brinser; Steven L.Dry photochromatic film
US5523757 *Feb 11, 1993Jun 4, 1996Resnick; Joseph A.Signal damping camouflage system and manufacturing method
US6195805Feb 27, 1998Mar 6, 2001Allegiance CorporationPowder free neoprene surgical gloves
US6224795Jul 26, 1999May 1, 2001Basf AktiengesellschaftLow-formaldehyde dispersion of microcapsules of melamine-formaldehyde resins
US6504161Jul 24, 2000Jan 7, 2003Sunspots, Inc.Radiation indicator device
US6586751Apr 30, 1999Jul 1, 2003Focal, Inc.Light source power tester
US6719931Jan 9, 2001Apr 13, 2004Basf AktiengesellschaftLow-viscosity, melamine-formaldehyde resin microcapsule dispersions with reduced formaldehyde content
US7018711Apr 20, 2002Mar 28, 2006Basf AktiengesellschaftMicro-capsules comprising a capsule core containing water-soluble substances
US7227158Nov 8, 2005Jun 5, 2007Jp Labs, Inc.Stick-on self-indicating instant radiation dosimeter
US7476874Feb 26, 2004Jan 13, 2009Jp Laboratories, Inc.Self indicating radiation alert dosimeter
US7956334 *Mar 9, 2007Jun 7, 2011School Corporation, Azabu University Medicine Educational InstitutionRadiation dosimeter for fluid very small substances, and method of measuring radiation dose
US8051441Mar 31, 2008Nov 1, 2011Nbcuniversal Media, LlcPlayer-readable code on optical media
US8097324 *May 14, 2008Jan 17, 2012Nbcuniversal Media, LlcEnhanced security of optical article
US8115182Oct 31, 2007Feb 14, 2012Gordhanbhai N PatelPersonal and area self-indicating radiation alert dosimeter
US8229276Sep 28, 2007Jul 24, 2012Nbcuniversal Media, LlcLimited play optical article
US8361587Mar 13, 2009Jan 29, 2013Nbcuniversal Media, LlcEnhanced security of optical article
US8488428May 14, 2008Jul 16, 2013Nbcuniversal Media, LlcEnhanced security of optical article
US8646106Sep 28, 2007Feb 4, 2014Nbcuniversal Media, LlcLimited play optical article
US8830806Jul 17, 2008Sep 9, 2014Warner Bros. Entertainment Inc.Optical disc with a theft deterrent coating
US8872134Mar 5, 2012Oct 28, 2014Jp Laboratories, IncSelf indicating radiation alert dosimeter
US9056948Mar 14, 2011Jun 16, 2015Follmann & Co. Gesellschaft Fuer Chemie-Werkstoffe Und Verfahrenstechnik Mbh & Co. KgMicrocapsules and production thereof
US9086489Feb 13, 2012Jul 21, 2015Jp Laboratories, IncPersonal and area self-indicating instant radiation alert dosimeter
US20040084631 *Oct 30, 2002May 6, 2004Eastman Kodak CompanyApparatus and method for radiation verification
US20040089961 *Apr 20, 2002May 13, 2004Dirk WulffMicro-capsules comprising a capsule core containing water-soluble substances
US20040214335 *Jul 19, 2002Oct 28, 2004Qiangyi LiUv irradiation control
US20050208290 *Aug 13, 2003Sep 22, 2005Patel Gordhanbhai NThick radiation sensitive devices
DE102009012455A1Mar 12, 2009Sep 23, 2010Follmann & Co. Gesellschaft Für Chemie-Werkstoffe Und -Verfahrenstechnik Mbh & Co. KgVerbesserte Mikrokapseln und ihre Herstellung
DE102010040564A1Sep 10, 2010Mar 15, 2012Henkel Ag & Co. KgaaMikrokapselhaltiges Wasch- oder Reinigungsmittel
DE102010040567A1Sep 10, 2010Mar 15, 2012Henkel Ag & Co. KgaaKosmetisches Mittel mit Mikrokapseln
DE102011082496A1Sep 12, 2011Mar 14, 2013Henkel Ag & Co. KgaaMikrokapselhaltiges Mittel
DE202007010668U1Jul 30, 2007Dec 18, 2008Follmann & Co. Gesellschaft Für Chemie-Werkstoffe Und -Verfahrenstechnik Mbh & Co. KgVerbesserte Mikrokapseln
EP1416294A1 *Oct 20, 2003May 6, 2004Eastman Kodak CompanyApparatus and method for radiation verification
EP2364773A1Sep 13, 2010Sep 14, 2011Follmann & Co. Gesellschaft für Chemie-Werkstoffe und -Verfahrenstechnik mbH & Co. KGImproved microcapsules and their manufacture
EP2433617A2Sep 9, 2011Mar 28, 2012Henkel AG & Co. KGaACosmetic composition containing microcapsules
WO1993018377A1 *Mar 3, 1993Sep 16, 1993Kossuth Lajos TudomanyegyetemUv dosimeter for visual checking
WO2002085510A1 *Apr 20, 2002Oct 31, 2002Basf AgMicro-capsules comprising a capsule core containing water-soluble substances
WO2004017095A2 *Aug 13, 2003Feb 26, 2004Gordhanbhai N PatelThick radiation sensitive devices
WO2004077097A2 *Feb 26, 2004Sep 10, 2004Jp Lab IncSelf-indicating radiation alert dosimeter
WO2010102830A2Mar 12, 2010Sep 16, 2010Follmann & Co. Gesellschaft Für Chemie-Werkstoffe Und Verfahrenstechnik Mbh & Co. KgImproved microcapsules, and production thereof
WO2011110368A2Mar 14, 2011Sep 15, 2011Follmann & Co. Gesellschaft Für Chemie-Werkstoffe Und -Verfahrenstechnik Mbh & Co. KgImproved microcapsules and production thereof
WO2013037575A1Aug 10, 2012Mar 21, 2013Henkel Ag & Co. KgaaAgent containing microcapsules
Classifications
U.S. Classification250/474.1, 430/138
International ClassificationG01T1/06, B01J13/04, C09K9/02
Cooperative ClassificationG01T1/06, B01J13/04, C09K9/02
European ClassificationB01J13/04, C09K9/02, G01T1/06
Legal Events
DateCodeEventDescription
Apr 17, 1994LAPSLapse for failure to pay maintenance fees
Jun 28, 1994FPExpired due to failure to pay maintenance fee
Effective date: 19940628